plate has 11 distinct synonyms spread across 7 of its 16 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
(baseball) base consisting of a rubber slab where the batter stands; it must be touched by a base runner in order to score
“he ruled that the runner failed to touch home”
a full-page illustration (usually on slick paper)
dish on which food is served or from which food is eaten
a rigid layer of the Earth's crust that is believed to drift slowly
the thin under portion of the forequarter
a main course served on a plate
“a vegetable plate”
the positively charged electrode in a vacuum tube
a flat sheet of metal or glass on which a photographic image can be recorded
structural member consisting of a horizontal beam that provides bearing and anchorage
a metal sheathing of uniform thickness (such as the shield attached to an artillery piece to protect the gunners)
a dental appliance that artificially replaces missing teeth
Synonyms, antonyms and the broader and narrower relations for plate come from Princeton University’s WordNet. Full sources and licences.